Rectifier construction for absorption type refrigerator

ABSTRACT

An absorption refrigerator in which a rectifier is located above the boiler and has two concentric pipes. The absorption solution that is moved upwardly from the boiler flows subsequently downwardly while the refrigerant and absorption medium vapors flow upwardly in the space between the two pipes. One of the pipes is so constructed as to form a series of narrow constrictions to the flow path above the zone in which heat is applied to the boilers so that both liquid and vapor are in counterflow but without interfering with each other.

United States Patent Asher et al.

[ 51 Feb. 11,1975

RECTIFIER CONSTRUCTION FOR ABSORPTION TYPE REFRIGERATOR inventors: Amram Asher, Oberengstringen;

Nicolas Eber, Unterengstringen. both of Switzerland Sarlab Akticngesellschaft, Zurich. Switzerland Filed: Feb. 12, 1974 Appl. No.: 441,808

Assignee:

Foreign Application Priority Data Feb. I3, 1973 Sweden "730L913 US. Cl. 62/496, 62/497 Int. Cl. F25b 15/04 Field of Search 62/440, 495, 496, 497

References Cited UNITED STATES PATENTS 4/1974 Lenning 62/496 Primary Examiner-William F. O'Dea Assistant ExaminerPeter D. Ferguson [57] ABSTRACT An absorption refrigerator in which a rectifier is located above the boiler and has two concentric pipes. The absorptionsolution that is moved upwardly from the boiler flows subsequently downwardly while the refrigerant and absorption medium vapors flow upwardly in the space between the two pipes. One of the pipes is so constructed as to form a series of narrow constrictions to the flow path above the zone in which heat is applied to the boilers so that both liquid and vapor are in counterflow but without interfering with each other.

8 Claims, 7 Drawing Figures mamm Hm 31864.93?

sum 1 OF 2 to condenser 10 absorber vessel PATENIED FEB] 1 I975 sum 2 or 2' FIG. 4

FIG. 3.

RECTIFIER CONSTRUCTION FOR ABSORPTION TYPE REFRIGERATOR BACKGROUND OF THE INVENTION Refrigerating apparatus are known provided with rectifiers that have narrow constrictions of uniform or almost uniform width. The constrictions formed in the structure function as a rectifier that ensures a fairly efficient counterflow heat exchange between the relatively cold solution that is rich in refrigerant and which flows in a downward direction and the relatively hot solution that is poor in refrigerant and flows in an upward direction. The rectifier construction additionally prevents the intermixing of rich and weak liquid which are located in different parts of the boiler by means of rising vapors. The smooth operation of the rectifier is necessary for an efficient boiler; this, in turn, creates an efficient refrigeration apparatus.

The above-described rectifiers, having a series of narrow constrictions, are simple and inexpensive to manufacture and their construction does not involve an increase of the wetted and hot surface of the boiler and therefore there is no increased consumption of corrosion inhibitor. In practice, however, rectifiers having a series of narrow constrictions have certain drawbacks and disadvantages which has reduced the efficiency of the refrigeration apparatus. For example, the constrictions in the rectifiers are extremely narrow, with a radial width not exceeding 1 mm. in order to carry out a satisfactory rectification. If the constrictions are made larger, then the proper rectification cannot be achieved, since the liquid and vapor flow in different locations in the constriction and there is no satisfactory counterflow exchange of heat and mass.

If a rectifier is provided with a series ofsmall constrictions of almost uniform width a given quantity of liquid is accumulated in a liquid column above each constriction and a vapor cushion is formed below the constriction. The size of both the liquid column and the vapor cushion is maintained more or less constant. The vapor passes through the constrictions and the liquid columns above them in the shape of small bubbles and the liquid flows downwardly on the pipe wall in the form generally of a thin film. In this state of equilibrium, the pressure drop above the constrictions is balanced by the liquid columns located above the constrictions. However, if additional heat is supplied to the apparatus in order to increase the capacity of the boiler, the flow of liquid and vapor increases and the state of equilibrium is upset since the balance between the pressure drop and the liquid columns above the constriction is not possible and the boiler therefore does not operate properly.

A result of the known rectifier structure having narrow constrictions of uniform or substantially uniform radial dimensions is to limit the boiler of a refrigeration apparatus to comparatively small capacity. A further disadvantage of such rectifiers is that precise accuracy in manufacturing these structures is necessary.

The present invention overcomes the abovedescribed disadvantages and drawbacks of known rectifier structures having narrow constrictions and at the same time preserves the rather considerable advantages of these types of structures.

An object of the present invention is to provide in each constriction of the present rectifier at least one corner or angle-shaped portion connecting a portion of greater width to one or more than one narrow portions. In this construction, the liquid flows by capillary action downwardly without preventing the vapor from flowing upwardly in counterflow to the liquid.

Each of the narrow portions is so dimensioned as to have a width not exceeding 1 mm.

The invention will now be more fully described with reference to the accompanying drawings, in which:

FIG. 1 is an elevational view, partly in section, of the boiler unit of an absorption refrigerator, including a rectifier constructed in accordance with the teachings of the present invention;

FIG. 2 is a side elevational view of the rectifier shown on an enlarged scale;

FIG. 3 is a cross-sectional view of the rectifier taken along the lines Ill-Ill of FIG. 2;

FIG. 4 is a cross-sectional view of the rectifier taken along the lines IVIV of FIG. 2;

FIG. 5 is an elevational view of the rectifier taken in the direction labeled V of FIG. 2;

FIG. 6 is an elevational view of a modified embodiment of the rectifier; and

FIG. 7 is a cross-section view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the boiler comprises two pipes 10 and 11 arranged concentrically. The pipes are connected to an absorber of the refrigeration apparatus by means of a heat exchanger 12. The inner pipe 10 is connected to the absorber vessel and conveys absorption solution to the boiler B, for example a solution rich in refrigerant, such as ammonia in water. Located inside the boiler and within the inner pipe 10 is a pump conduit 13. The inner pipe 10 is shown closed at its upper end 14 where it is welded to the conduit pipe 13 at a location above the rectifier 15. The latter is situated directly above the heated part of the boiler.

As seen in FIG. 1, heat is supplied to the boiler by an electric heating cartridge 16 that is connected to an energy source by means of electrical conduits 17, which may be an AC power supply or a battery. It will be noted that the heating cartridge 16 is disposed within a metal sleeve 18 that is welded to the outer pipe 11. A flue pipe 19 is illustrated as also being welded to the pipe 11. Thus, the boiler can be heated alternatively by the electric heating cartridge 16 or by a gas or kerosene burner (not shown) but which may be located below the flue pipe 19.

When the boiler unit B of the present refrigeration apparatus is heated, hot vapors of ammonia and water raise the absorption solution through the pump conduit 13 and the vapors are conveyed to a condenser (not shown), by means of a vapor conduit 20 that forms an extension of the outer pipe 11. The liquid raised or 'elevated in pump conduit 13 flows into the outer pipe 11 and downwardly through the heated portion of the boiler B and further through the heat exchanger 12 to the upper part of the absorber. When the weak solution passes the heated portion of the boiler B in the outer pipe 11, additional vapors are generated and flow upwards through the rectifier in counterflow to the partly enriched solution. It should be apparent that in the rectifier of the present construction an exchange of heat and mass occurs between the solution and vapors in order to increase the concentration of refrigerant of the vapors.

A heat exchange is performed in an effective manner by means of rectifiers of the type shown in FIGS. 2-5. As seen in the drawings, above and below each rectifier 15 are indentations 21 made in the outer pipe 11. As particularly shown in FIG. 3, the indentations 21 spatially engage the outer surface of inner pipe to thereby maintain the inner pipe concentric with outer pipe 11. It will be noted in FIGS. 2 and 5 that the rectifier has constrictions 22 in the flow path of the partly enriched solution. The outer pipe 11, as seen in FIG. 4, is compressed in a manner so that the crosssection of the pipe is reduced at predetermined locations within the rectifier 15 of the boiler B and corner or angle-shaped portions 23 are formed at opposite ends. Thus, the outer pipe 11 is provided with wide portions 24 connected by narrow portions 25. It will be observed that the wide portions 24 are mainly for the passage of vapor and the narrow portions 25 are principally for the passage of liquid. Both the liquid and vapor are in counterflow in the corner-shaped portions 23. Furthermore, when the present rectifier operates, both counterflow between the working media and the intense contact between liquid and vapor are ensured. Moreover, the boiler operates in a stable manner and properly with a varying heat supply and within a large range of capacity.

FIG. 3 shows the indentations 21 of the outer pipe 11 of the rectifier maintaining the inner pipe 10 in a concentric position. Furthermore, FIG. 4 discloses the constriction 22 having narrow portions 25, wide portions 24, and diametrically opposed corner or angle-shaped portions 23.

The rectifier section 15, as seen in FIG. 2, illustrates corner-shaped sections 23 disposed one above the other. Nevertheless, it is possible to change the pattern, as seen in FIG. 6, wherein each constriction 22 is turned 90 relative to the adjacent constriction. FIG. 7 is a cross-sectional view of the alternate embodiment shown in FIG. 6 and shows the relationship of the constrictions 22 to each other. The operating characteristics of this constriction is also favorable.

What is claimed is:

1. An absorption refrigerating apparatus provided with a boiler having a rectifier, said rectifier comprising two pipes in which one pipe is located concentrically within the other pipe to form a space therebetween functioning as a flow path, the raised absorption solution in said apparatus flows downwardly in said space while the refrigerant and the absorption medium vapors flow upwardly therein, said flow path having a series of constrictions formed in a part of one of said pipes above a zone in which heat is supplied to said boiler wherein each constriction has at least one angled, corner-shaped part forming a wide portion and at least one narrow portion that are interconnected.

2. A rectifier as claimed in claim 1 wherein each angled corner-shaped part is so constructed and formed whereby liquid flows downwardly by capillary action without preventing the vapor from flowing upwardly in counterflow to the liquid.

3. A rectifier as claimed in claim 1 wherein the outer pipe of said concentric pipes is provided with means for maintaining said pipes in concentricity.

4. A rectifier as claimed in claim 3 wherein said means are spaced indentations projecting internally in said outer pipe.

5. A rectifier as claimed in claim 1 wherein each constriction has two diametrically opposed angled cornershaped parts and two narrow portions respectively connecting said wide portions.

6. A rectifier as claimed in claim 5 wherein a series of said angled corner-shaped parts are disposed one above the other.

7. A rectifier as claimed in claim 5 wherein in a series of angled corner-shaped parts each part is positioned approximately relative to an adjacent angled corner-shaped part.

8. A rectifier as claimed in claim 1 wherein each narrow portion has a width that does not exceed 1 mm. 

1. An absorption refrigerating apparatus provided with a boiler having a rectifier, said rectifier comprising two pipes in which one pipe is located concentrically within the other pipe to form a space therebetween functioning as a flow path, the raised absorption solution in said apparatus flows downwardly in said space while the refrigerant and the absorption medium vapors flow upwardly therein, said flow path having a series of constrictions formed in a part of one of said pipes above a zone in which heat is supplied to said boiler wherein each constriction has at least one angled, corner-shaped part forming a wide portion and at least one narrow portion that are interconnected.
 2. A rectifier as claimed in claim 1 wherein each angled corner-shaped part is so constructed and formed whereby liquid flows downwardly by capillary action without preventing the vapor from flowing upwardly in counterflow to the liquid.
 3. A rectifier as claimed in claim 1 wherein the outer pipe of said concentric pipes is provided with means for maintaining said pipes in concentricity.
 4. A rectifier as claimed in claim 3 wherein said means are spaced indentations projecting internally in said outer pipe.
 5. A rectifier as claimed in claim 1 wherein each constriction has two diametrically opposed angled corner-shaped parts and two narrow portions respectively connecting said wide portions.
 6. A rectifier as claimed in claim 5 wherein a series of said angled corner-shaped parts are disposed one above the other.
 7. A rectifier as claimed in claim 5 wherein in a series of angled corner-shaped parts each part is positioned approximately 90* relative to an adjacent angled corner-shaped part.
 8. A rectifier as claimed in claim 1 wherein each narrow portion has a width that does not exceed 1 mm. 